The present invention relates to a unit cell for a solid electrolyte type fuel cell, which employs a solid electrolyte to induce electrochemical reaction so as to produce electrical energy, and its related manufacturing method and, more particularly, a unit cell for a solid electrolyte type fuel cell, having a solid electrolyte sandwiched between a pair of electrodes, and its related manufacturing method.
In recent years, attempts have heretofore been made to provide a solid electrolyte type fuel cell (solid oxide electrolyte type fuel cell: hereinafter preferably referred to as “SOFC”) through the use of an electric power generator element with a structure in which a solid oxide electrolyte medium is sandwiched between two electrodes, i.e., a fuel electrode (anode) and an air electrode (cathode) which are supplied with hydrocarbon fuel, such as methane, and oxidizing gas such as oxygen or air, respectively, to produce an electric power output. The SOFC has a high electric power generating efficiency and a exhaust heat recovering capability and is expected as a third-generation fuel cell.
Japanese Patent Application Laid-Open Publication No. H9-50812 discloses a structure which includes a porous electrode substrate composed of a sintered body of ceramic electrode material powder with a porosity rate varying in a direction of a thickness.
Japanese Patent Application Laid-Open Publication No. 2000-200614 discloses a structure which includes a porous electrode substrate composed of a sintered body of ceramic electrode material powder.
It has been proposed to provide a so-called DLR cell (Plasma Sprayed Thin-Film SOFC for Reduced Operating Temperature, Fuel Cells Bulletin, pp. 597 to 600, 2000).
Japanese Patent Application Laid-Open Publication No. H7-45297 and Japanese Utility Model Application Laid-Open Publication No. S63-106063 disclose a SOFC which includes a current collector, made of Nickel felt, in addition to electrodes, for collecting power output generated with a fuel electrode and an air electrode. With such a SOFC, a large number of cell elements are connected in series or in parallel in use and a joint member (hereinafter referred to as “I.C.” (interconnector)) is required to electrically connect the cell elements with respect to one another. There are some instances where such an I.C. has a current collecting function.
Further, owing to the SOFC adapted to generate electric power output through the use of the fuel electrode and the air electrode that need hydrocarbon fuel gas, such as methane, and oxidizing gas such as oxygen and air, it is required to use a member which forms gas flow passages to introduce gases to respective surfaces of the electrodes. There are some instances where such gas flow passages have the I.C. functions, respectively.